螺旋压缩弹簧断裂分析

材料为50CrVA钢的弹簧在疲劳试验时发生批次性断裂，对断裂弹簧的断口进行宏、微观观察和能谱分析，对弹簧的组织进行检查，并测试其硬度，结合弹簧的制造工序，对裂纹的形成原因进行综合分析。结果表明:弹簧的断裂性质为镉致脆性断裂，镉脆发生在除氢工序，裂纹起源于镀镉过程中产生的凹坑处，弹簧镉脆断裂与除氢过程中的超温及喷丸与总检工序中防锈不当而产生的锈蚀有关。通过加强防锈处理及温度控制可以预防弹簧镉脆失效。

Fracture Analysis of Spiral Compression Springs

Batches of 50CrVA compression springs fractured during the process of fatigue test. In order to find out the failure mode and cause of the springs, macro and micro observation, EDS analysis, metallurgical examination and hardness testing were carried out. The results show that the compression springs fractured due to cadmium embrittlement. Cadmium embrittlement crack came into being during the process of removing hydrogen and originated from surface pit formed during cadmium plating process. Higher temperature during removing hydrogen and improper rust protection during the process of shot peening and general inspection are the main reasons for the cadmium embrittlement cracking of the springs. The cadmium embrittlement cracking of the springs can be prevented by strengthening rust protection during shot peening and general inspection process and controlling the temperature during removing hydrogen.